Giants, revenants and vikings populate the world of »Hervarar saga ok Heiðreks«, an account of the medieval Scandinavian rulers Hervör and her son, Heiðrekr. Some form of the tale has existed since at least the late tenth century, when part of it was incorporated into the Old English »Widsith«, and the story has afterwards been retold in a variety of forms by poets, scholars and songwriters. This book is an analysis of the changes underwent by the saga during its early transmission from the Middle Ages up until the end of the seventeenth century. It presents details of all known manuscripts containing the saga, an expansive overview of major narrative variants between four redactions of »Hervarar saga, Hervarar rímur« and related metrical ballads, as well as information on key figures who influenced the saga in early modern times, such as Brynjólfur Sveinsson, bishop of Skálholt in Iceland and Olaf Verelius, royal antiquarian to the Swedish king Charles XI.